Posted on Nov 23, 2012

Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope`s three-pronged power plug. You can avoid this problem by using the ground-noise tester shown. Powered by two 9-V batteries, the circuit dissipates power only while push-to-test switch Sl is depressed. Noise pulses that reach IC2A`s switching threshold of about 1.5 to 1.8 V create a logic transition that triggers the monostable multivibrator IC3, which stretches the pulse to produce a visible blink from LED Dl.

Click here to download the full size of the above Circuit.

You set the noise reference level by adjusting threshold-adjust potentiometer Rl, which lets the circuit respond to minimum pulse amplitudes ranging from about 0 to 1 V. For convenience, you can use a onetum potentiometer for Rl and calibrate the dial by applying an adjustable de voltage, monitored by an accurate voltmeter.

Leave Comment

characters left:

New Circuits



Popular Circuits

Frequency Divider
Logarithmic light-meter circuit
Bug Detector Circuit
Solar Panel Based Charger And Small LED Lamp
Traffic Light Project
car parking sensor circuit using infra
ceiling fan regulator motor speed
Micropower Low Noise Boost Converters with Output Disconnect
Battery voltage indication circuit